1. Technical Field of the Invention
The present invention relates to a line-type inkjet recorder, and more specifically to an inkjet recorder that prevents discharge failure accompanying ink quality change occurring in a non-discharge nozzle during printing.
2. Description of the Related Arts
A line-type inkjet driving device is conventionally known which selectively controls ink discharge to form a monochromatic or full-color image on a print recording medium (hereinafter indicated as paper), such as a paper sheet.
The inkjet driving device of this type has a nozzle (hereinafter indicated as non-discharge nozzle) that does not perform discharge even once depending on an image to be printed. This non-discharge nozzle does not discharge ink during printing. For example, if ink is discharged from a nozzle adjacent to the non-discharge nozzle, due to driving of a discharge ink chamber thereof, ink near a discharge port of the non-discharge nozzle may vibrate. After a lapse of long non-discharge time under the condition that the ink near the discharge port of the non-discharge nozzle vibrates as described above, there arises a problem that, as a result of contact of the ink near the discharge port with air, this ink changes in quality and also its drying is promoted, which is likely to cause ink discharge failure and non-discharge.
Thus, to address such a problem, for example, an inkjet recorder disclosed in Patent document 1 is suggested.
An inkjet recording method performed in the inkjet recorder disclosed in Patent Document 1 measures the continuous non-discharge time for each nozzle and discharges non-image ink droplets from each nozzle in a predetermined discharge pattern during print operation to thereby achieve ink droplet discharge maintaining processing without stopping the print operation. This method maintains highly accurate printing by measuring the continuous non-discharge time for each nozzle from print driving data for each nozzle and forcibly discharging ink droplets from each nozzle in a discharge pattern predetermined separately from the print driving data during print operation.
[Patent Document 1] Japanese Patent Application Laid-open No. 2002-178534
However, the inkjet recorder disclosed in Patent Document 1 prevents discharge failure in the continuous non-discharge nozzle by way of so-called “idle discharge” that periodically discharges non-image recording ink droplets from the non-discharge nozzle in a less conspicuous manner. However, this method controls idle discharge by the continuous non-discharge time, so that, when the continuous print time or the continuous non-discharge time is long, ink consumption unnecessarily increases for operations other than printing, which is not economical.